Resistor



Patented Feb. 12, 1935 PATENT OFFICE RESISTOR James B.

Grenagle, Baltimore, Md.,

assignor of one-half to William W. Varney, Baltimore, Md.,

and one-half to Universal Alloys, Incorporated, Baltimore, Md., a corporation of Maryland No Drawing. Application January 17, 1930, Serial No. 421,603

2 Claims. (01. ear-1c) The object of my invention is the production of an electric resistor thatwill stand high temperature and may be used in high temperature smelting in place of the electric arc, thereby 5 avoiding the addition of tion of the smelting from the carbon of the are.

A further object of my invention is the production of a resisting material of high refractory nature suitable for use in electric furnace work, especially where a crucible is used packed within a surrounding body or mass of my resistor.

A further object of my invention is an improved process for making the ingredient zirconium carbide used in the formation of my re-- sistance material.

A further object of my invention is the method of treatment of my resistance material for forming resistors.

My resistor is especially adapted for electric furnaces, mufles, calcining, tempering, and tempering furnaces and melting; also, for heating bars ispace heaters), electric ranges, electric irons and stoves, and, in fact, for any apparatus in which an electric resistance element may be 25 used.

With the foregoing and other objects in view, my invention consists of the methods employed, combination and arrangement of systems and means as hereinafter specifically provided, but it is understood that chames, variations and modifications may be resortw to which come within the scope of the claims hereunto appended.

I physically mix boron nitrid and zirconium carbide, and if for use in formed resistors I crush, grind and mix the clients; if it is to be used as a loose resisting material, I crush or grind to a desired size or mesh, depending upon the resistance required. The boron nitrid acts as a nonconductin tory substance; the conductor and as a in. refractory.

en these two substances are mechanically mixed in granular form, they form a resistance material capable of producing intense heating effect, the finer the ingredients the less the resistance.

One method I use in making my resistor consists oi reducing the mixed ingredients to a fine powder and then packing the same into an iron 50 mould under rather high pressure; as an example, using a 1 in. iron pipev about 1 ft. long,

carbon in the produc-.

article, or a loose, granular ance element that will also, that practically mahlwresistance and highiy-refraczirconium carbide acts as a.

packing the powder intov this pipe under about 4000 lbs. pressure, then heating to approximately 2900 F. and allowing to cool, resulting in a very tenacious yet brittle resistance.

In this specification and claims, when I use term, resistor", I mean either a formed, rigid mass.

In a resistance furnace I make large bars in formed. or moulded shape with the powder above mentioned moistened with water, or a binding '10 material such as, starch, or molasses, and trowel the same into moulds under a considerable pressure or tamping. These moulds are thoroughly dried, heated or calcined and produce a resist- I make my zirconium carbide, used as above, as follows: I fuse together zirconium oxide (ZrOz) and carbon; 1 mix Zl'Oz and graphite, in the proportion of lb. graphite with 4 lbs. ZrOz, and 20 fuse in an arc furnace providedwith a neutral, or zirconium, content I have found that a considerable variation in the percentage of the ingredients used may be allowed without aiiecting the utility of the resistor;

any fluid or cementing in gredient may be used, as in the extremely high temperature the binding material is probably eliminated and a cohesion of the primary elements is suflicient to maintain the entity of the so product.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. The process of forming an electric resistor comprising mechanically mixing boron nitrid and the product obtained from fusing zirconium oxide and carbon at a high temperature, then compacting the mixture so formed and heating to a temperature approximately 2900 F.

2. A process of manufacturing a resistance 40 element which comprises mixing substantially lb. of graphite with 4 lbs. of ZrOz, fusing the same my an electric arc, then reducing the resultant to suflicient fineness to co-mingle with other in gredlents, then co-mingling said resultant with boron nitrid in the substantial ratio of 75% of boron nitrid and 25% of the said resultant, compacting the same and then heating to approximately 2900 F. v

- JAMES B. GRENAGLE.

the 5 stand approximately 15 

